Truck Repair: L10 Cummins, low oil pressure, coolant level

Question
I have a L10 Cummins in a 1993 Freightliner that ships at an idle up to 1100 or 1200 RPM on acceleration or when shiffing gears. It skips on the upshift and downshift, but does not skip when coasting in gear and reaccelerating. Also at no paticular intereval, then shutdown light will come on and the truck will decellerate. Also the cruise and jakebrake will not work. It has been hooked up to a computer and shows no codes.
Thanks
Robert

Answer
There are a few sensors that will not always log codes.Speedo sensor is one if the yoke on the rear is loose it will slip.The cruise & brake not working could be because of that sensor too or a bad switch.The computor will help check the switches & to make sure the throttle sensor is all working correctly.The shutdown light will cause them not to work too.Shutdown could be throttle sensor,low oil pressure,low coolant level,high water temp, or high oil temp.But usually those will log a code.